Can't find a"why"! Help!

Maybe you need to think about it from the why not point of view? You can do this! You deserve it we all do.

I got fed up with being fed up.

I also got into running. I get so much out of it. Trail running, adventure racing, obstacle courses are all so much fun.

My personal strategy is to concentrate on good eating habits, and to follow my training plans.
I keep track of my weight, but don't track calories very closely.

You could pick some fitness goal that the children could be involved with and take it from there.
(fun runs, inflatable obstacle courses, hikes up a local mountain, etc)

One bit of advice I read somewhere that helped me, was to not worry about losing weight...
Instead, find some type of activity (exercise/sport) that you love doing, and focus on that. When you find something you love, you want to do more or get better, and the focus on health and nutrition can grow quite naturally from that.

I know that is just one snippet of advice, and not suited to every situation or person, but it was something that clicked with me, and it's working. I am much more positive and staying on track better now that it's not about losing weight, it's about doing something I enjoy - the weight loss is a benefit that is slowly happening on the sidelines.